Retractable gymnastic backboard

ABSTRACT

A retractable gymnastic backboard includes a first frame member having a positioning groove and a screw hole, a second frame member having a positioning groove, a bendable board member having two distal ends thereof respectively engaged into the positioning grooves of the first and second frame members, and an adjustment rod member having a middle handhold portion, a screw portion disposed at one end and threaded into the screw hole of the first frame member, and a coupling portion disposed at the other end and pivotally coupled to the second frame member for allowing rotation of the adjustment rod member to move the first frame member relative to the second frame member and to further adjust the height of the board member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates a gymnastic backboard for use in stretching the back and/or waist of a user and more particularly, to a retractable gymnastic backboard that can be conveniently adjusted to change its height.

2. Description of the Related Art

FIG. 1 shows a conventional gymnastic backboard for use in stretching a user's back and/or waist. According to this design, the gymnastic backboard 1 comprises a base frame 2, and a board member 2. The base frame 2 is a flat frame, having a first end 4, a second end 5, a first positioning groove 6 disposed near the first end 4, and a plurality of second positioning grooves 6′ disposed near the second end 5 and spaced from one another in direction from the second end 5 toward the first end 4. The board member 2 is bendable, having one end engaged into the first positioning groove 6 and the other end selectively engaged into one of the second positioning grooves 6′. When in use, the gymnastic backboard 1 is put on the floor beneath the user's back (waist), and then the user can stretch the back (waist) to train the muscles of the back (waist). By means of changing the engagement position between the board member 3 and the second positioning grooves 6′, the height of the gymnastic backboard 1 is relatively adjusted to fit different exercise requirements or different users.

This design of gymnastic backboard is functional; however, it has drawbacks as follows:

1. When wishing to adjust the height of the board member 3, the user must disengage the board member 3 from the respective second positioning groove 6′ and then bend the board member 3 to a proper curvature and then insert the board member 3 into another selected second positioning groove 6′. In order to support the user's body weight, the board member 3 is made having a certain hardness and resilience. When removing the board member 3 from the respective positioning groove 6′ or engaging the board member 3 into another selected second positioning groove 6′, the user must apply much force to curve the board member 3.

2. The adjustment of the height of the board member 3 is limited to the number of the second positioning grooves 6′. In order to increase the adjustment range, the length of the base frame 2 must be relatively increased. However, increasing the size of the base frame 2 results in a storage and delivery inconvenience.

Therefore, it is desirable to provide a gymnastic backboard that eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is an object of the present invention to provide a retractable gymnastic backboard, which can be conveniently adjusted to change the height to fit different users.

It is another object of the present invention to provide a retractable gymnastic backboard, which can rapidly be adjusted to change the height.

It is still another object of the present invention to provide a retractable gymnastic backboard, which can conveniently be adjusted to change the height with less effort.

To achieve these objects of the present invention, the retractable gymnastic backboard comprises a first frame member having a positioning groove and a screw hole, a second frame member having a positioning groove, a bendable board member having two distal ends respectively engaged into the positioning groove of the first frame member and the positioning groove of the second frame member, and an adjustment rod member having a middle handhold portion, a screw portion at one end thereof and threaded into the screw hole of the first frame member, and a coupling portion at the other end thereof and pivotally coupled to the second frame member, thereby rotating the adjustment rod member can move the first frame member relative to the second frame member to further adjust the interval between the first frame member and the second frame member and the height of the board member.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view of a gymnastic backboard according to the prior art.

FIG. 2 is a perspective view of a retractable gymnastic backboard according to a preferred embodiment of the present invention.

FIG. 3 is an exploded view of the retractable gymnastic backboard according to the preferred embodiment of the present invention.

FIG. 4 is a bottom view of the retractable gymnastic backboard according to the preferred embodiment of the present invention.

FIG. 5 is a side view of the retractable gymnastic backboard according to the preferred embodiment of the present invention.

FIG. 6 is similar to FIG. 5 but showing the height of the retractable gymnastic backboard adjusted.

DETAILED DESCRIPTION OF THE INVENTION

A shown in FIGS. 2-5, a retractable gymnastic backboard 10 provided by the preferred embodiment of the present invention comprises a first frame member 20, a second frame member 30, an adjustment rod member 40, and a board member 50.

The first frame member 20 is a flat frame, having a positioning groove 21 transversely disposed at one side, namely, the rear side, a screw hole 22 longitudinally disposed on the middle of the other side, namely, the front side, and two coupling rods 23 forwardly extending from the front side and arranged in parallel at two sides of the screw hole 22.

The second frame member 30 is a U-shaped frame, having a positioning groove 31 transversely disposed at one side, namely, the rear side, a coupling hole 32 longitudinally disposed on the middle of the other side, namely, the front side, and two arms 33 forwardly extending from the front side and arranged in parallel at two sides of the coupling hole 32. The arms 33 each define therein a guide hole 34 for receiving the coupling rods 22 of the first frame member 20 respectively.

The adjustment rod member 40 has a handhold portion 42 on the middle, a coupling portion 41 axially integrally extending from one end of the handhold portion 42 and inserted into the round hole 32 of the second frame member 30, a locating groove 44 extending around the periphery of the coupling portion 41 near the free end, and a screw portion 43 axially extending from, the other end of the handhold portion 42 and threaded into the screw hole 22 of the first frame member 20. The handhold portion 42 has a non-circular cross section for the grasping of the hand positively. Further, a locating pin 35 is transversely inserted into the peripheral wall of the coupling hole 32 and engaged into the locating groove 44 of the adjustment rod member 40 to prohibit axial movement of the adjustment rod member 40 relative to the coupling hole 32 of the second frame member 30, thereby allowing rotary motion of the adjustment rod member 40 relative to the second frame member 30. When rotating the adjustment rod member 40, the first frame member 20 is moved relative to the second frame member 30, and the interval between the first frame member 20 and the second frame member 30 is relatively adjusted.

The board member 50 is a thin, resilient tough board bent into an arched shape and engaged with the two distal ends thereof into the positioning groove 21 of the first frame member 20 and the positioning groove 31 of the second frame member 30. The board member 50 has a rectangular through hole 51 longitudinally disposed on the middle to enhance the flexibility of the board member 50. When installed in the first frame member 20 and the second frame member 30, the board member 50 is kept in an arched shape for supporting the user's back and/or waist during stretching exercise. Further, when the interval between the first frame member 20 and the second frame member 30 is changed, the height (curvature) of the board member 50 is relatively changed.

Referring to FIGS. 5 and 6, the height and length of the retractable gymnastic backboard 10 are H₁ and L₁ respectively when the retractable gymnastic backboard 10 is kept in the shape shown in FIG. 5; when the user rotated the adjustment rod member 40 to adjust the height and length of the retractable gymnastic backboard 10 from H₁ and L₁ shown in FIG. 5 to H₂ and L₂ shown in FIG. 6 respectively, the relation between these two conditions can be expressed by the following inequation. (1) if L₁>L₂, then H₁<H₂ (2) if L₁<L₂, then H₁>H₂

Therefore, when the user wishes to adjust the height of the retractable gymnastic backboard, the user needs only to rotate the adjustment rod member 40. The adjustment is stepless to fit different users or different requirements.

Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. For example, the first frame member can be made having two arms each defining a guide hole and the second frame member can be made having two coupling rods respectively inserted into the guide holes of the arms of the first frame member; the adjustment rod member can be made having a coupling hole at one end remote from the screw portion and the second frame member can be made having an coupling portion pivotally coupled to the coupling hole of the adjustment rod member; the number of the arms and the coupling rods may be relatively increased. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A retractable gymnastic backboard comprising: a first frame member having a positioning groove and a screw hole; a second frame member having a positioning groove; a bendable board member having two distal ends respectively engaged into the positioning groove of said first frame member and the positioning groove of said second frame member; and an adjustment rod member having a handhold portion, a screw portion threaded into the screw hole of said first frame member, and a coupling portion pivotally coupled to said second frame member.
 2. The retractable gymnastic backboard as claimed in claim 1, wherein said second frame member has at least one guide hole; said first frame member has at least one coupling rod slidably inserted into the at least one guide hole of said second frame member.
 3. The retractable gymnastic backboard as claimed in claim 1, wherein said first frame member has at least one guide hole; said second frame member has at least one coupling rod slidably inserted into the at least one guide hole of said first frame member.
 4. The retractable gymnastic backboard as claimed in claim 1, wherein said handhold portion of said adjustment rod member has a non-circular cross section.
 5. The retractable gymnastic backboard as claimed in claim 1, wherein said board member has a through hole at a middle thereof.
 6. The retractable gymnastic backboard as claimed in claim 1, wherein said second frame member has a coupling hole, which receives the coupling portion of said adjustment rod member.
 7. The retractable gymnastic backboard as claimed in claim 1, wherein the coupling portion of said adjustment rod member has a coupling hole; said second frame member has a coupling portion pivotally coupled to the coupling hole of the adjustment rod member. 